class AssertionError(AssertionError):

def __init__(self, *args):

    BuiltinAssertionError.__init__(self, *args)

    if args: 

        self.msg = str(args[0])

    else: 

        f = sys._getframe(1)

        try:

            source = py.code.Frame(f).statement

            source = str(source.deindent()).strip()

        except py.error.ENOENT:

            source = None

            # this can also occur during reinterpretation, when the

            # co_filename is set to "<run>".

        if source:

            self.msg = exprinfo.interpret(source, f, should_fail=True)

            if not self.args:

                self.args = (self.msg,)

        else:

            self.msg = None